package org.langqiao.filter;

/**
 * 中文乱码过滤器，重写getParamter()方法
 */
import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class SetCharacterEncodingFilter implements Filter {
 
 
    // ----------------------------------------------------- Instance Variables
 
 
    /**
     * The default character encoding to set for requests that pass through
     * this filter.
     */
    protected String encoding = null;
 
 
    /**
     * The filter configuration object we are associated with.  If this value
     * is null, this filter instance is not currently configured.
     */
    protected FilterConfig filterConfig = null;
 
 
    /**
     * Should a character encoding specified by the client be ignored?
     */
    protected boolean ignore = true;
 
 
    // --------------------------------------------------------- Public Methods
 
 
    /**
     * Take this filter out of service.
     */
    public void destroy() {
 
        this.encoding = null;
        this.filterConfig = null;
 
    }
 
 
    /**
     * Select and set (if specified) the character encoding to be used to
     * interpret request parameters for this request.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
    throws IOException, ServletException {
 
        HttpServletRequest httprequest = (HttpServletRequest) request;
        if ("GET".equals(httprequest.getMethod())){
        	// 将httpRequest进行包装
        	EncodingHttpServletRequest wrapper = new EncodingHttpServletRequest(httprequest, encoding); 
        	chain.doFilter(wrapper, response);
        }else {
        	request.setCharacterEncoding(encoding);
        	response.setContentType("text/html;charset=" + encoding);
        	chain.doFilter(request, response);
        }
    }
 
 
    /**
     * Place this filter into service.
     *
     * @param filterConfig The filter configuration object
     */
    public void init(FilterConfig filterConfig) throws ServletException {
 
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        if (value == null)
            this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
            this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
            this.ignore = true;
        else
            this.ignore = false;
 
    }
 
 
    // ------------------------------------------------------ Protected Methods
 
 
    /**
     * Select an appropriate character encoding to be used, based on the
     * characteristics of the current request and/or filter initialization
     * parameters.  If no character encoding should be set, return
     * <code>null</code>.
     * <p>
     * The default implementation unconditionally returns the value configured
     * by the <strong>encoding</strong> initialization parameter for this
     * filter.
     *
     * @param request The servlet request we are processing
     * @return String
     */
    protected String selectEncoding(ServletRequest request) {
 
        return (this.encoding);
 
    }
}